Body signal sensing electrode apparatus



March 3, 1970 J P. BUNN 3 1 I BODY SIGNAL SENSING ELECTRODE APPARATUS 7 Filed Feb. 10. 1966 FIG.2

l4 INVENTOR.

- ,4 JOHN P. BUNN I1 BY Agent United States Patent 07 3,498,291 BODY SIGNAL SENSING ELECTRODE APPARATUS John P. Bunn, Atlanta, Ga., assignor to Lockheed Aircraft Corporation, Burbank, Calif. Filed Feb. 10, 1966, Ser. No. 526,425 Int. Cl. A61b 5/04 US. Cl. 1282.06 2 Claims ABSTRACT OF THE DISCLOSURE An improved body electrode for sensing electrical impulses present on the skin of a person. The electrode is useful, for example, for sensing electrical impulses generated by the operation of the heart and to be recorded on an electrocardiogram. The present electrode requires no conductive paste or other externally applied substances for enhancing the conductivity of the contact region between the electrode and the skin. Instead, the present electrode includes an impervious, body contact surface which promotes and retains a. film of perspiration between the electrode and the skin, and the saline property of the perspiration enhances the conductivity of the electrode.

This invention relates in general to a body electrode and in particular to a body electrode useful for sensing electrical impulses produced by the operation of the human body and appearing at selected locations on the skin surface thereof.

In performing a medical examination of a person, it frequently is desirable to measure electrical potentials produced by the functioning of various bodyorgans as an aid to the diagnosis of the health of such organs. An example of this is found in the field of cardiology, wherein a physician may cause a recording to be takenof the electrical potentials produced by the operation of the heart and occurring at various locations on the skin of the person. Such a recording commonly is known as a cardiogram.

In making a cardiogram suitable electrodes are positioned on the body of the person at various locations thereon, these locations being well known to those skilled in the art. For example, one prior art type of electrode includes a generally concave cup-like member having a passage communicating with the concave portion and having a flexible squeeze bulb communicating with the passage. In the operation of this type of electrode, the squeeze bulb is squeezed and the concave portion is positioned at a desired location on the body. The squeeze bulb is then released, whereupon atmospheric pressure causes a portion of the skin under the concave portion to be forced into the concave portion and the electrode assembly to be firmly forced against the body of the person. A suitable conductive electrode paste usually is contained in the concave portion to enhance the conductivity of the electrode-skin junction.

Although the electrode described above is satisfactory for some applications, this electrode also has a number of disadvantages. One of these is the near-requirement that this electrode can be used only in conjunction with imperforate metallic the skin.

3,498,291 Ce Patented .Mar. 3, 1970 the aforementioned conductive paste, and such pastes are messy and bothersome in their application and in the requirement of post-use cleanup. Moreover, the suction cup type of electrode, if improperly applied, may cause bruising of the skin of the patient.

An additional problem concerning the use of prior art electrodes arises when it is desired to utilize a number of electrodes in conjunction with some electrode-supporting apparatus or device, the intent of such apparatus being to enable a number of electrodes to be'quickly and conveniently positioned on the body of the patient, possibly for extended periods of time, without the necessity of having each electrode individually positioned by or under the direction of a physician. One example of such apparatus is found in the pending United States patent application entitled Body Electrode Support Garment, Ser. No. 509,941, filed Nov. 26, 1965, now US. Patent No. 3,409,007 and assigned to the same assignee as the present invention. Use of prior art body electrodes with apparatus of this type produces an arrangement which not only is cumbersome and which requires frequent cleaning because of the required use of electrode paste, but also which may be quite uncomfortable when worn for an extended period of time by a person.

when pressed against the body ofja person for extended periods of time. An electrode having the foregoing attributes is the subject of this invention.

Accordingly, it is an object of this invention to provide an improved body electrode.

Another object of 'this invention is to provide a body electrode which does not require theapplication of electro'de paste; I

A further object of this invention is to provide a body electrode which may comfortably be held in contact with the body of a user for extended periods of time.

Still another object of this invention is to provide a body electrode which does notsubject the body of a user to the possibility of bru ing or other physical damage to Yet another object of this invention is to provide a body contact electrode which advantageously can'be used in c'ombination with an electrode support device.

A still further object of this invention is to provide a body contact electrode which advantageously can be used in combination with an electrode support garment of the type worn in the manner of a vest by a person.

The exact nature of this invention as well as other objects and advantages thereof will be readily apparent from consideration of the following specification relating to the annexed drawing in which:

FIGURE 1 shows a perspective view of an embodiment of a body electrode according to this invention; and

FIGURE 2-shows asection view taken alon'gline 22 of FIGURE I. Y

Stated generally, the body electrode of this invention includes a platelike element which is to be snugly disposed against the body of a user at a location whose electrical potential is to be measured. The platelike element is fabricated from material which is not toxic to the skin of the user and which is not tarnished or otherwise adversely affected by perspiration from the users body. Appropriate mounting structure is associated with the platelike element so that this element can be removably secured to the vestlike garment or other device which may be used to position one or more body electrodes on the body of a user.

More particularly and with reference to FIGURES 1 and 2 of the drawing, there is shown a body electrode indicated generally at and having a generally circular planar plate electrode element 11. The surface area of electrode element 11, which need not be circular depends on the region of the body at which it is desired to take a measurement of potential. By way of example only, an electrode element having a diameter approximately equal to the diameter of a half dollar has been found to be suitable for cardiography. To the back 12 of electrode element 11 there is secured by an suitable technique, such as soldering or the like, a fastening device such as nut 13.

Assuming that the electrode described herein is being used in conjunction with a support apparatus such as the vestlike garment of the above-referenced co-pending application, a portion of the fabric of such supporting device is shown as support apparatus 14. At each location on the support apparatus where a body electrode is to be positioned, a suitable hole 15 is formed in the garment by punching or by any other suitable technique. A suitable grommet 16 then is inserted through this hole to protect the edges formed by the hole-making process and to provide support and spacing for the electrode element 11 with respect to the support apparatus 14. As best shown in FIGURE 2, grommet 16 includes a cuplike element 17 having a sleeve portion 21 extending through hole 15 and also having a rim portion 22 arcuately shaped so as to present a convex surface 23 to back 12 of electrode element 11. Grommet 16 is completed by a second annular member 24 which is engagingly received over sleeve portion 21 and which has an arcuate section corresponding to the arcuate portion of rim portion 22.

The relative dimensions of nut 13 and sleeve portion 21 are chosen so that the nut can just be received within the sleeve portion. Once this is done a body electrode is secured to the support apparatus 14 with a screw 25 threadingly engaged in nut 13. Washers 26 and 27 are positioned on the shank of screw 25, with washer 27 'being dimensioned to transfer the thrust of the screwto sleeve portion 21 of grommet 16. A suitable electric lead or connector 28 conveniently may be received between Washer 26 and washer 27 to establish electrical communication between the electrode element 11 and a cardiograph or other suitable apparatus utilizing the electrical potentials sensed by the electrode.

The electrode element 11 preferably is fabricated from a metal which does not adversely affect the skin of a user and which itself is not affected by the presence of body perspiration and the like. By way of example only, it has been found that an electrode element of 14 kt. filled gold functions suitably, the gold-filled exterior of the electrode element having the added advantage of low electrical resistivity.

Electrode element 11 as mounted on support apparatus 14 is spaced outwardly a short distance from the support garment because of the physical contact between back 12 of the electrode element and convex surface 23 of grommet 16. This ensures that the electrode element 11 will be firmly disposed against the body of a user when the support apparatus is donned by the user, so that a good electrical contact will be established with the electrode. After the electrode ha be n p si ioned ag inst the body of a user in this manner for a short while, a thin film of perspiration forms between the outer surface of electrode element 11 and the skin covered by this electrode element. This thin layer of perspiration, because of its saline nature, acts as a conductive substance analo gous to the electrode paste of the prior art to enhance further the conductivity of the electrode-body interface. It should be emphasized that the electrode of this invention is not limited to use in conjunction with the abovereferenced vestlike garment, inasmuch as any device or technique which retains this electrode in perspirationinducing engagement with the body is sufiicient.

When nut 13 has been inserted in sleeve portion 21 and screw 25 is engaged in the nut and tightened, washer 27 abuts with the end of sleeve portion 21 so that the electrode element 11 is positively and firmly engaged against convex surface 23, thus ensuring that the electrode element is positively positioned with respect to support apparatus 14. Of course, the use of a nut and a screw to effect this securement is exemplary only, and any suitable fastening device such as a quick-disconnect or Dzus-type connector could also be used. Furthermore, the use of a two-piece grommet is by way of illustration only and is not intended to limit.

It should be understood, of course, that the foregoing relates to only a preferred embodiment of the invention and that numerous modifications or alterations may be made therein without departing from the spirit and the scope of the invention as set forth in the appended claims.

What is claimed is:

1. A flexibly supported dry body contact electrode which senses electrical potential present on the surface of the skin without the added presence of an externally 'applied substance for enhancing the conductivity of the body contact, comprising in combination:

a thin flexible support web having an aperture therein;

an electrode element having an electrically conductive skin contact surface all of which is smooth, rigid, and impervious to perspiration for contact with the body of a user to retain an electrically conductive film of perspiration between said surface and the body of a user;

said electrode element having securement means on a side thereof opposite to said surface;

said flexible support web including connective means disposed through said aperture and detachably connected with said securement means to retain said electrode element in place on a side of said flexible support web with said electrode element surface facing away from said web;

said connective means including spacing means extending a predetermined distance outwardly from said side of said web in annularly surrounding relation with said aperture to be in contacting engagement with said electrode element when the electrode element is retained in place on said web, said spacing means keeping said electrode element and said skin contact surface spaced apart from said side of the flexible support web to enable said skin contact surface when contacting the body of a user to be aligned relative to said web to be coextensive with the body;

said connective means including a rigid sleeve portion retained on said Web and extending through said aperture, said sleeve portion terminating at one end thereof adjacent said electrode element in a rim member annularly surrounding said end and extending said predetermined distance outwardly from said side of said web to constitute said spacingmeans; and

said connective means and said securement means being connected to engage said electrode element securely against said annular rim member.

2. Apparatus as in claim 1, wherein:

said securement means includes a first threaded member secured to said opposite side of said electrode element, the external dimensions of said first threaded member permitting such member to be received Within said end of said sleeve portion,

said annular rim member engaging said electrode element in a region surrounding said first threaded member; and

said connective means including a second threaded member threadedly engaging said first threaded member, said second threaded member engaging the end of said sleeve portion opposite said one end so that said threaded engagement forces said electrode element into engagement with the annular rim member to maintain said skin contact surface spaced apart from said side of the flexible support member.

References Cited UNITED STATES PATENTS Thrasher et a1. 128404 Kelly 128418 Berman 128418 Sullivan 128417 Kahn 1282.06 Darling 1282.06

WILLIAM E. KAMM, Primary Examiner 

